Compilation error when installing dependencies with yarn

Hi Jared,

I am trying to run this example but I can't due I get the following error while installing the dependencies with `yarn`.

yarn install v1.3.2
info No lockfile found.
[1/4] 🔍 Resolving packages...
[2/4] 🚚 Fetching packages...
[3/4] 🔗 Linking dependencies...
[4/4] 📃 Building fresh packages...
[1/7] ⡀ sdl2
[2/7] ⡀ ppx-env: ninja: Entering directory `lib/bs'
[3/7] ⢀ matchenv: [2/3] Building src/index.mlast
[4/7] ⢀ bs-platform
error /Users/arielschiavoni/Projects/opensource/reprocessing-example-cross-platform/node_modules/matchenv: Command failed.
Exit code: 2
Command: bsb && cp lib/bs/native/index.native matchenv
Arguments:
Directory: /Users/arielschiavoni/Projects/opensource/reprocessing-example-cross-platform/node_modules/matchenv
Output:
ninja: Entering directory `lib/bs'
[1/3] Building Matchenv.cmi
[2/3] Building src/index.mlast
[3/3] Building src/index.mlast.d
[1/1] Building src/index-Matchenv.cmj
FAILED: src/index-Matchenv.cmj /Users/arielschiavoni/Projects/opensource/reprocessing-example-cross-platform/node_modules/matchenv/lib/js/src/index.js src/index-Matchenv.cmi
/usr/local/lib/node_modules/bs-platform/lib/bsc.exe -bs-package-map matchenv -bs-package-output commonjs:lib/js/src -bs-assume-no-mli -bs-no-builtin-ppx-ml -bs-no-implicit-include -I . -I src -w -30-40+6+7+27+32..39+44+45+101 -nostdlib -I '/Users/arielschiavoni/Projects/opensource/reprocessing-example-cross-platform/node_modules/bs-platform/lib/ocaml' -no-alias-deps -color always -bs-re-out -bs-super-errors -o src/index-Matchenv.cmj -c src/index.mlast

We've found a bug for you!
command line

The module or file Pervasives can't be found.

- If it's a third-party dependency:
- Did you list it in bsconfig.json?
- Did you run `bsb` instead of `bsb -make-world`
(latter builds third-parties)?

Thanks!

まず `yarn install` を再現し、`node_modules/matchenv` で失敗しているビルドを調査します。特に `lib/bs` と `bsb` コマンドの出力を確認してください。`bs-platform` が `Pervasives` を見つけられない理由を調査します。完了の条件は、例の依存関係がコンパイルエラーなしでインストールされることです。

索引モデルが issue の本文から書いたものです。